1. Field of the Invention
The present invention relates to a silver halide photographic light sensitive material having improved antistatic property and particularly, to a photographic light sensitive material having both improved antistatic and adhesion resisting properties without adversely affecting photographic characteristics.
2. Description of the Prior Art
Since a photographic light sensitive material comprises in general, an electrically insulating support and photographic layers, accumulation of electrostatic charge on the photographic material results from contact friction between the surface of the photosensitive material and the surface of the same or a different material, and from separation of materials superposed on one another, each of which takes place frequently in manufacturing the photosensitive materials and in the course of the using them. The accumulated electrostatic charge causes various problems. The most serious problem is the appearance of dotted spots or branchy or feathered streaks on a photographic film upon development processing, caused by exposure of the light sensitive emulsion layers by sparks generated by discharge of accumulated electrostatic charge before development. Such spots and streaks are so-called static marks and they markedly impair or completely spoil the value of the photographic film. For instance, on the occasion that the static mark makes its appearance on an X-ray film for medical or industrial purpose, there is a danger of wrong diagnosis. Static marks are very troublesome because they can not be ascertained until development processing is complete. Moreover, the accumulated electrostatic charge is responsible for the induction of secondary problems. The surface of a photographic film is susceptible to adhesion of dust and the uniform coating of photographic layers becomes difficult.
As described above, such electrostatic charge is often accumulated during the manufacture and the use of the photographic materials. More specifically, in the process of manufacturing them, the accumulation of electrostatic charge results from, for instance, contact friction induced between a photographic film and a roller used, contact friction arising from the winding of a photographic film, separation of the support surface from the surface of the topmost emulsion layer upon the rewinding of the photographic film and so on. When using the finished articles, the accumulation of electrostatic charge is caused when the back surface of a photographic film contacts the surface of the topmost emulsion layer during rewinding of a wound film with the other take up shaft, or the contact of an X-ray film with instrument parts or a fluorescent intensifying screen and separation of the former from the latter in an automatic X-ray photograph-taking apparatus. In addition, electrostatic charge arises from contact with the wrapping material. The static marks induced on the photographic light sensitive material by accumulated electrostatic charges through the above-described motions are revealed more plainly and increase in number with an increase in the sensitivity of the photographic light sensitive material and the processing speed. Particularly, photographic light sensitive materials have recently been confronted with many instances in which they are processed under drastic conditions providing high sensitivity, high-speed coating, high-speed photographing, high-speed automatic processing and so on. Under these circumstances, the generation of static marks is more frequent.
The best way to avoid the problems resulting from the accumulation of electrostatic charge is to enhance the electric conductivity of the photographic film and thereby quickly disperse the electrostatic charge induced thereon and discharge the electrostatic charge. Such being the case, methods for improving the electric conductivities of the support, various surface layers of photographic light sensitive materials have been proposed, and various hydroscopic substances and water soluble inorganic salts, certain surface active agents, polymers and the like have been tried for this purpose. Examples of the substances which have been used to improve electric conductivity include polymers such as disclosed in U.S. Pat. Nos. 2,882,157; 2,972,535; 3,062,785; 3,262,807; 3,514,291; 3,615,531; 3,753,716; 3,938,999, etc.; surface active agents such as disclosed in U.S. Pat. Nos. 2,982,651; 3,428,456; 3,457,076; 3,454,625; 3,552,972; 3,655,387, etc.; zinc oxide, semiconductors, colloidal silica, etc as disclosed in U.S. Pat. Nos. 3,062,700; 3,245,833 and 3,525,621. However, many of these substances are highly selective in their effectivenesses. Namely certain substances exhibit sufficient antistatic effect only when used in conjunction with certain supports, photographic emulsions and other photographic elements, but are entirely useless when applied to different supports and photographic elements and, further, under some circumstances they adversely affect the photographic properties which make matters even worse.
In particular, much difficulty has been encounted attempting to provide antistatic property to hydrophilic colloidal layers, and even if the antistatic property has been improved to an extent, it was often been attended by undesirable side effects such as an insufficient reduction in surface resistance under low humidity, adhesion problems between the same photographic light sensitive materials or between a photographic light sensitive material and another material under conditions of high temperature and humidity, etc.
On the other hand, there have been instances when despite the excellent antistatic effect upon the hydrophillic colloidal layers, certain substances could not be used because they adversely affected the photographic characteristics of the photographic emulsion layers, such as sensitivity, fog, graininess, sharpness, etc. For instance although polyethylene oxide series compounds have been known to possess the antistatic effect, they have frequently yielded undesirable effects on the photographic characteristics such as increase in fog, desensitization, deterioration of graininess and so on. Particularly, it has been difficult to establish such techniques as to give effectively the antistatic property to sensitive materials of the kind which have supports having on the both sides thereof coated photographic emulsion layers, such as direct radiographic sensitive materials for medical use. As described above, the application of conventional antistatic agents to photographic light sensitive materials has been very difficult and that, in many cases such agents have been restricted to only few uses.